Giant magneto-optic response in rare-earth doped glasses and manufacturing of related devices and sensors

The magneto-optic effect is the core part of optical isolators and widely used in optical sensors. The market of optical isolators was estimated to be $0.7B in 2016 and is expected to grow at 5% per annum while that of optical fibre sensors has grown continuously in the last two decades and from $3.38B in 2016 it is expected to reach $5.98B in 2026.

To date fiberized devices and sensors based on the magneto optic effect have relied on simple telecom fibres or hybrid solutions with expensive crystals. This project proposes new manufacturing technologies for high performance optical isolators and current/magnetic field sensors aimed to replace the traditional hybrid approach based on crystals with novel glasses/fibres.

This approach relies on our recent discovery that slightly-doped Gd-doped glass fibres exhibit a giant magneto-optic coefficient, similar to crystals, yet maintaining low-cost, low loss and high compatibility with fibres. This proposed programme spans from the investigation of giant magneto-optic effect in slightly doped glasses to the manufacture of specialty silica fibres, through the design of fiberized isolators and novel fibre based frequency conversion devices, and their combination in suitable systems for applications in security, industry and medicine.

Although the initial effort will relate to the fabrication and characterization of novel glass compositions for glasses and fibres with giant magneto-optic response, the newly developed fibres will then be used to manufacture novel sensors and devices for selected practical industrial implementations in optical isolators and magnetic/current sensing.

This project aims to develop novel manufacturing technologies for devices and sensors based on the magneto-optic effect. This is based on the newly discovered response of Gd-doped glasses, that exhibited a response consistent with a Verdet constant 100 times larger than conventional telecom or spun fibres and even larger than conventional crystals (TGG) commonly used to manufacture optical isolators.

The main application of this proposal outcome resides in the industrial exploitation for the many applications where a strong response to the magnetic field is fundamental: high power fibre lasers for metal processing, security, oil/gas industry, magnetic anomalies detection, power delivery lines and specialty optical fibres, just to cite a few.

The UK economy has important players in all these fields. For example, SPI lasers, JK lasers and Fianium are major manufacturers of optical fibre lasers for marking / material processing, Fibercore is the world leader of specialty fibre manufacturing, Salunda, Sensa, Schlumberger are major players in the field of oil/gas support services.

The global market for high power fibre lasers exceeded $1B and the UK holds more than 10% of the business - most of which lies in companies spun out from the ORC. Current applications are now focussed mainly on metal processing, with an increase interest from defence. All the lasers need optical isolators, which are currently manufactured overseas. It is reasonable to expect that the possibility to manufacture optical isolators locally would increase the competitivety of British laser companies.

From the knowledge point of view, this project will contribute to advances in multiple ways: it will develop new materials, new fibres, new techniques for in-fibre devices and optical isolators, and novel sensors which can be exploited in other fields for a wealth of applications. New techniques include: novel in-fibre devices, novel optical isolation techniques, sensors capable to measure 1nT magnetic fields, sensors capable to measure sub-ns current pulses. Although this proposal has Engineering targets like the manufacture of four deliverables for industrial partners, it will also include Scientific advances related to a number of subjects: materials with giant magneto-optic properties, the study of Gd-ion solubility and the effect of their concentration effect on the magneto-optic property to name but a few.

From the societal point of view, the successful completion of this project would increase the availability of high quality well paid jobs in the photonics industry (photonics manufacturing have an added value that is three times larger than the average value for UK manufacturing). It could also make medical scanners cheaper and more sensitive, thus improving their availability in NHS facilities.

On a long term (10-50 years) basis, it is reasonable to assume that the market for fibre laser sources will continue to increase and replace more conventional lasers, especially for application in the processing and marking of different types of materials. Similarly, as two of the largest manufacturers of optical fibre lasers are based in the UK, it is realistic to expect that the fraction of the world laser market taken over by British companies will increase. It is also reasonable to expect a more significant impact of high power fibre lasers on manufacturing as a critical component (the optical isolator) will become cheaper and readily available because of the improved sovereign capabilities.